In the thermometer field it is often a problem for technical personnel to read the temperature display because the display is rigidly attached to the sensor. Personnel having the responsibility for monitoring the temperature of, for example, food products during storage and during periods of display at the point of sale have need for a means of observing such temperatures with convenience and accuracy. Articles whose temperatures are to be monitored are frequently in positions such that output screens or scales rigidly attached to their associated temperature sensing probes are not readily readable. Similar problems arise when the temperatures to be measured are associated with air leaving outlet grilles or louvers; with human orifices within which temperatures are commonly measured for medical diagnostic purposes; or with insert wells in reactor or other types of pressure vessels whose temperatures must be monitored for control of process progress, efficiency or safety.
Solutions to these problems have included instruments that hold their highest or last reading. An example of an instrument utilizing this solution is a mercury-in-glass fever thermometer having a restriction in the passage between the sensing bulb and the scale. When a thermometer of this type, having registered a patient's temperature, is removed from the patient and exposed to a cooler environment, the restriction prevents the retreat of the mercury column and allows the physician to read the patient's body temperature without significant error. Electrical instruments having rigidly connected sensors and scales, such as tong type clamp-on ammeters have, similar problems and have utilized a similar solution. The solution is comprised of a mechanical lock by which the operator can lock the unseen meter needle, causing the needle to hold its position while the instrument is removed and the needle position is observed and recorded.
These solutions, though reasonably effective for their limited purposes, are less desirable or even ineffective and harmful when "on line" observation of rapidly changing temperatures is required. Examples of such rapidly changing temperatures are those which occur in refrigerated food storage cases during evaporator defrost cycles or during compressor operating cycles; those which occur in the air outlet ducts of heating and air conditioning systems as the heating or conditioning equipment cycles on/off or changes capacity; or those which occur in chemical or other processes.
Traditional thermometers, in addition to being extremely fragile are noted for their propensity for rolling off tables where they are casually laid and fall to their destruction. The trapezoidal non-rollable case design of the instrument of the present invention helps prevent such accidental destruction from occurring.
The present invention resulted from the inventor's observation of these problems and his successful efforts to solve them. The present invention, therefore, is directed toward a self-contained portable thermometer having a digital display and a temperature sensing probe which is pivotally connected to the portion of the thermometer containing the display thereby allowing the display to be rotated to a conveniently readable position with respect to an observer once the probe has been placed in the desired position.